(A)

(H)

(T)

(F)

Cranks With Planks Present:

<> Converting a Rowing Dinghy to
Sail <>

By PERCY W. BLANDFORD

[First published in THE RUDDER in 1954, this gem
is Blandford at his best. If you've never checked out his books you'll
be amazed at his output over the years. Plans for his canoes and kayaks
are still available, I'm told, from Clark-Craft. These include folding
kayaks and canvas boats. -- COD]

MOST rowing dinghies are
suitable for conversion to sail. The result will not be a racing boat,
although she will be able to sail on all usual points and give her
owner immense pleasure while he is using his skill to make the wind do
the work. To convert a rowing dinghy to sail, besides the mast and sail
with the attendant rigging, there must be some form of a keel to
prevent leeway, and a rudder deeper than is needed merely for rowing.
It is an advantage if the conversion can be done without affecting the
suitability of the boat for rowing or for an outboard motor. It is also
worth while to choose a rig which can be dismantled and stowed within
the boat if necessary.

Most rowing dinghies are of comparatively
shallow draft so that the addition of sail without increasing the keel
surface will result in a craft capable of sailing downwind only, an
attempt to sail in any other direction resulting in probably as much
leeway as forward progress. The sail could be added first and the
dinghy used providing its limitations are realized.

There are many possible rigs for a small boat.
For a knockabout type of conversion the sail plan should consist of a
single sail. If cost is to be kept low there should be a minimum number
of fittings to buy. A sail which answers these requirements and is
easily stowed is the balanced lug (A).
The beginner is unlikely to come to any harm while sailing with this
rig, yet he can carry out all the usual sailing maneuvers and use his
boat to go places.

Of course there cannot be any universal
sailing rig suitable for all dinghies, but most dinghies of the yacht
tender type, whether round bottomed or hard chine or built with plywood
or planked skin, conform to a general proportion and can be converted
to sail with a good chance of success. The conversion described in this
article is based on a common 10 foot dinghy. For other size boats the
main dimensions can be altered proportionately. The sail size errs on
the small side and will certainly not overcanvas an average rowing
dinghy hull.

The mast, yard and boom are all 9 feet long.
The mast should have a maximum diameter of about 2-1/2 inches and taper
to about 1-1/2 inches at the top. Suitable woods are fir or spruce. It
could be shaped up from square stock, but for this sort of craft it is
simplest to use a natural pole with the bark stripped off. A natural pole
may have a few lengthwise cracks or shakes, but they do not matter
provided they are small. Clean up the pole with draw knife and plane
and then sand. The thickest part should come near gunwale level.

In a 10 foot dinghy the mast is located about
18 inches back from the stem. It is unlikely that there will be a
rowing thwart there and the simplest support for the mast is a board
fixed across the gunwales. This may have a central hole for the mast (B), or if the boat will have to negotiate low
bridges frequently there could be a U shaped notch with a metal keeper
to swing across (C).

The foot of the mast should have a tenon cut
in it to fit a block screwed to the hog [keelson] (D).
Arrange
this
so
that
the mast stands upright.

The mast may be stiff enough to stand without
stays, but it is more likely to need a forestay and a pair of shrouds.
These are best made of steel wire, but they could be fiber rope. To
support them fit two wooden chocks on each side of the top of the mast.
Cut a slot below them for the sheave (E)
which takes the halliard.

The shrouds may be in a continuous
length, looped around the top of the mast and taken down to shroud
plates (F) on each gunwale, about 6
inches aft of the mast. Rigging screws could be used, but for economy
the old fashioned lanyards are satisfactory.

If the mast passes through a hole in its
thwart the forestay may be arranged with a lanyard to a ring on the
stem head in the same way as the shrouds. If the mast is arranged so
that it may be lowered it is better for the forestay to be brought to a
pair of blocks, with a halliard leading aft to a conveniently placed
cleat (G).

Forestay & Shrouds

The yard should be kept light. It is
nine feet long and may be of fir or spruce, with a thickness of about
1-1/2 inches where the halliard is attached and tapering a little
towards the ends (H). A bamboo pole of
the same size may be substituted for solid wood.

Lightness is not needed in the boom. In
fact a reasonable amount of weight is desirable. The boom may be solid
wood about 1-1/2 inches in diameter, or a square with rounded corners
makes a modern section. This is also 9 feet long. The only work on
these two spars is to drill a 3/8 inch hole near each end.

It is best to have the sail (I)
professionally made to the sizes given. If you make it yourself use a
light grade sailcloth, reinforce the corners well, and rope all around
if possible. In any case rope the short luff and 12 inches or so along
the head and foot of the sail. Put cringles or substantial eyelets in
each corner and a row of eyelets along the head. A row of reef points
may be arranged about 15 inches up from the foot.

Fasten the corners of the sail to the yard and
boom with light line, taken around the spars and through the holes. Do
not stretch excessively or the set of a new sail will be spoiled.
Fasten the head of the sail to the yard with marline hitching (J) through the eyelets. Fasten a short tack
line to the forward end of the boom. After the sail is hoisted by the
halliard the tack line is hauled back to a cleat on the side of the
mast. The yard may have an eye attached to connect with a traveler on
the mast (K).

A simpler arrangement is to merely tie the
halliard to the yard, preferably using a topsail halliard bend (L). Experiment to get the best set. The yard
should clear the forestay as it swings over. When the best set is
found, mark the yard and fix the cleat for the tack line. Put a similar
cleat on the other side to take the halliard. Alternatively the
halliard may be taken through a small block and led aft to a cleat on a
thwart so that it becomes possible to lower the sail without moving
forward.

The sheet to control the sail (M)
is eye spliced to the boom and led direct to the hand. There is no need
for the complication of tackle to give extra purchase on this small
sail.

[COD: Here I
disagree with Blandford.
Put a block on the boom. Knot both ends of the sheet.

[Your sheet should
be long enough that, when the sail is 90 degrees to the centerline, you
can hold the end comfortably, and then some. Next, put a block on the
rudder head, or on a lanyard on either quarter (stern corner). Untie
the knot in one end of the sheet and run it through the new block. Knot
it. Now, when running before the wind you can let the sail out and the
two knots stop you from ever losing the sheet. You grab it somewhere in
the middle, depending on where you're sitting in the boat, to sheet the
sail when running, or you can tug on the end passing through the stern
block.

When heading upwind, you grab the
knot at the boom end as the sail comes inboard, and sheet with
that. The other knot stops at the stern block and you now have a 2:1
purchase. Even on such a small sail it's a lot more relaxing to have a
sheet purchase. This is an old canoe-sailing trick. Of course, you can
also pass on block #2, and put a carabiner or snap hook on one end of
the sheet. The hook snaps onto a padeye, or sturdy loop of line, on the
bottom of a thwart or on the bottom of the boat as in (T). You
use the sheet the same way, but it's not "double-ended".]

If the boat already has a rudder its blade may
be lengthened or a longer blade may be substituted depending on the
design of the steering gear. If a rudder has to be made one with a
hinged blade will be most convenient. The blade may be of aluminum
alloy or galvanized steel, in which case it will stay down under its
own weight, or it may be of wood and held down by rubber under tension.
Make the stock of two pieces of 1/2 inch plywood separated by a piece
slightly thicker than the blade (N). The
stock should reach from just above the keel level to a few inches above
the transom. Thicken the top and slot it to take the tiller (O).

The hangings may be regular gudgeons
and pintles (P) or pieces of strip steel
of about 1/4 by 1/8 inch section may be bent and screwed on so as to
mate with a 1/4 inch rod hinge pin (Q).

If the blade is of metal it need not be more
than 1/4 inch thick. If plywood is used it should be 1/2 inch. Pivot
the blade on a bolt. With a wooden blade arrange a stop (R)
so that the rubber does not pull the blade too far.

Rudder with Bungee

The simplest method of providing a grip
on the water is by using a leeboard. This is not as good looking as
some sort of a lifting keel, but it is simple and quite effective.
Large craft which favor this method of providing keel surface are the
Thames sailing barges and many Dutch coasters and sailing yachts. On
large boats there are two boards, but only the one on the lee side is
lowered. In a dinghy the board is light enough to be lifted over when
going about. The board may be of plywood or solid wood, about 5/8 inch
thick, large enough to project about 2 feet below the keel line; and
about 8 inches wide (S).

Leeboard

Shape it to a streamlined section below
the water. The simplest method of hanging the leeboard is by a rope
from the bottom of the boat resting against a peg in a rowlock socket (T). The only objection to this is that it does
not allow fore and aft adjustment and the main rowlock socket is likely
to be too far aft for correctly balancing the underwater profile with
the sail plan.

The more conventional way of adding keel
surface is by building in a watertight casing to take a drop keel or
centerboard. For a small dinghy the simplest arrangement and the one
that takes up the least room in the boat is a daggerboard which pushes
straight down its trunk instead of hinging up. The forward edge of the
daggerboard should be about 2 feet aft of the mast.

The daggerboard may be made of marine plywood
or solid wood, about 5/8 inch thick, or 1/4 inch metal as described for
the rudder blade. The underwater part of a wooden daggerboard should be
shaped and streamlined in the same way as a leeboard. The daggerboard
trunk needs to be braced securely in the boat as there may be
considerable sideways pressure on it when sailing with the wind abeam.
Its arrangement will depend on the particular boat. Most craft built
for rowing only do not have a keel wide enough to permit the cutting of
a slot without weakening the cut members. In such a case it is better
and simpler to have the daggerboard off center, passing through a slot
in the skin to one side of the keel. This will not affect the
performance of the boat. The trunk should be made so that its top comes
above the waterline (U). If it comes
level with the top of the thwarts that usually is high enough and is
convenient for fitting.

Make the trunk with plenty of clearance
around the daggerboard and shape it so that the board will have a
slight rake aft. The box may be built of 5/8 inch plywood glued and
screwed together, or slightly thicker solid wood may be used. If solid
wood is used have the grain of all pieces going the same way so that
any expansion or contraction is uniform and unlikely to strain the
joints or cause cracks. Curve the bottom of the trunk to suit the skin
and cut away any ribs or other structural members so that it will bed
down properly.

Mark the position of the slot on the skin and
cut it out by drilling holes at each end and sawing between them. Leave
the final trimming to size until the trunk [missing line] under way it
is advisable to use a wood glue which sets hard. It is better to bed
the trunk down on a piece of canvas liberally coated with one of the
flexible stopping compositions which never sets hard. Screw the parts
from below.

How the top of the trunk is fitted will depend
on its relation to thwarts and other parts. It may get sufficient
support by being notched into a thwart or a gangplank may be fitted
between two thwarts (V). Build up the
top of the daggerboard (W). A metal
board will stay down under its own weight. There are two ways of
fitting a wooden board so that it will stay down under normal
circumstances, but will rise if it hits an obstruction. A rubber strap
may be hooked over the top (X) or
friction can be provided inside the trunk by rubber nailed on each side
of the board (Y).

Daggerboard

If the dinghy also is towed behind a
power boat or driven by an outboard motor it may be worth while making
a plug to fit the top of the trunk when the daggerboard is removed,
otherwise water may be forced up the trunk at speed and give you wet
pants or some unnecessary bailing.

The various sizes mentioned should give
satisfactory sailing with an average dinghy. In the first trials under
sail experiment with various positions for attaching the halliard to
the yard and with various degrees of tension on the tack line. Your
position in the boat also will have considerable effect on her sailing
performance. With the wind aft you may be near the stern, but as the
wind comes abeam or forward of it you probably will get the best
results by sitting near amidships.